(1) Field of the Invention
This invention relates to a high data rate magnetic write head and more particularly to a multi-layer stitched magnetic write head design.
(2) Description of the Related Art
Magnetic read heads, often referred to as inductive read heads, must be designed in such a way that the magnetic flux extends across the air bearing surface into the magnetic media as much as possible. A cross section view of a conventional magnetic read/write head is shown in FIG. 1. As shown in FIG. 1 a magnetic sensor 16 is placed adjacent to the air bearing surface 30 of the head between a first ferromagnetic shield 10 and a second ferromagnetic shield 18 ferromagnetic shield.
The second ferromagnetic shield 18 also serves as the first pole piece 18 for the write portion of the head. A first non-magnetic gap layer 20 is formed on the first pole piece 18 and determines the gap 12 between the first pole piece 18 and the second pole piece 26 at the plane of the air bearing surface (ABS) 30. A second non-magnetic gap layer 22 is formed on the first non-magnetic gap layer 20 beginning a first distance 32 away from the ABS plane 30. The beginning of the second non-magnetic gap layer 22 defines the point where the gap 12 between the first pole piece 18 and the second pole piece 26 begins to widen. A layer of wiring 28, imbedded in a layer of insulating material 24, is formed on the second non-magnetic gap layer 20. An additional insulation layer 25 may be used to provide a smoother surface on which to form the second pole piece 26. The second pole piece is formed over the first non-magnetic gap layer, the second non-magnetic gap layer, and the additional insulation layer 25. It is advantageous to have the first distance 32 as small as possible in order to have the optimum distribution of magnetic flux.
U.S. Pat. No. 5,805,391 to Chang et al. describes a write head with a recessed stitched yoke on a planar portion of an insulation layer defining the zero throat height, or the point where the gap between pole pieces begins to widen. A second pole piece if formed of two pole piece components stitched together, or placed in contact to reduce the non-magnetic gap between the two pole components to zero.
U.S. Pat. No. 5,802,700 to Chen et al. describes a method of making a planarized thin film magnetic write head with submicron trackwidth.
U.S. Pat. No. 5,878,481 to Feng et al. describes a pole trimming method of forming a magnetic transducer structure.
In the design of magnetic write heads for high track per inch or low trackwidth applications it is important to have the throat height as small as possible. The throat height is the distance from the ABS end of the poles to point where the non-magnetic gap between the poles begins to widen, reference number 32 in FIG. 1. A stitched pole design can be used to improve the throat height but it is also necessary to have a recessed yoke design. The recessed yoke design provides a separation between the second pole piece, reference number 26 in FIG. 1, and the air bearing surface at the point where the second pole piece curves to provide an increased non-magnetic gap width.
It is a principle objective of this invention to provide a magnetic write head having multi-layer stitched poles, a small throat height, a recessed yoke design, and a planar top surface.
It is another principle objective of this invention to provide a magnetic write head having multi-layer stitched poles, a small throat height, and a recessed yoke design.
These objectives are achieved by using a multi-layer stitched pole design. A non-magnetic gap layer is formed on a layer of ferromagnetic material. A first pole piece is then formed on the non-magnetic gap layer. A notch is formed in the first pole piece to define the throat height. A second pole piece, recessed from the first pole piece is then formed making contact with the first pole piece. A third pole piece, recessed from the second pole piece is formed making contact with the second pole piece. The first, second, and third pole pieces form a stitched pole since there are regions of zero non-magnetic gap between the first pole piece and the second pole piece and between the second pole piece and the third pole piece. The notch in the first pole piece defines the throat height, the recessed second and third pole pieces form a recessed yoke, and the structure can be made planar.